The present disclosure relates generally to equipment utilized and operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides for cutting windows for lateral wellbore drilling.
In the well-known process of drilling a lateral wellbore, a window is typically milled through the side of a casing string, and then the lateral wellbore is drilled by passing a drill string through the window. When milling through either “pre-milled” aluminum wrapped window joints or casing strings, it is often difficult to get a milling tool to start to cut, due to a tendency of the milling tool to “walk” in a direction of rotation of the milling tool. This situation is worsened by a mis-match between a curvature of the milling tool and a curvature of the material it is attempting to cut.
Lateral displacement of the milling tool during the milling operation causes the window to be malformed, leading to difficulties in passing the drill string through the window, installing completion equipment in the lateral wellbore, etc. Therefore, it may be seen that improvements are needed in the art of cutting windows for lateral wellbore drilling.